Greek philosophy and especially the Platonic-Aristotelian tradition distinguished between an ordinary inferential kind of thought often called discursive thought, and a kind of thought, which is non-discursive or intuitive. The usual term for the former in Greek is dianoia for the latter nous and noesis. It goes back to some of the most famous passages in Plato and Aristotle such as the divided line in the Republic and the Metaphysics XII, which discusses God's thought. Then the Neoplatonists combined Plato and Aristotle, added certain features of their own and thus created the notions that are listed below. Emilsson argues that the distinction lived on throughout the Middle Ages and to some extent beyond even if it eventually ceased to be in ordinary use. Aspects of it played a role for some of the great early modern philosophers. Descartes, Pascal and Spinoza are some examples. The concept of intuition is very much behind Spinoza's notion of seeing things sub specie aeternitatis.[1] Likewise, there is indeed something of this ancient distinction at work in Kant's notions of intuition and understanding.

Of the many characteristics attached to intuition only one has survived in mainstream Anglophone philosophy, namely the notion of non-inferential knowledge. Though, the idea that there is some foundation of knowledge which itself is not inferred from anything else has of course been fiercely attacked, according to Emilsson. In continental philosophy matters are more complicated. Some other aspects of intuition survive there, partly through German idealism.[2] Werner Beierwaltes and others have shown it to be directly influenced by Neoplatonism as well as by Plato and Aristotle and partly through Bergson who drew directly on Plotinus.[3] Emilsson also notes that various other aspects of the ancient intuition now are making a comeback into philosophical currency for instance through the holism of Quine and Davidson. The ancient notions then as they appear in Plotinus are listed below.[4] Here I will not attempt to discuss them at any length though we will return to them later on.



Intuitive Thinking Discursive Thinking
Non-inferential Inferential
A-temporal Temporal
Grasps all at once Grasps objects piecemeal
Non-propositional Propositional
Non-representational Representational
Infallible Fallible



The enduring significance of Platonic philosophy is unquestioned. Some will have it that almost everything written in European philosophy is, footnotes to Plato.[5] Its main tenet, have survived to this very day and is vitalized by modern physics. Roger Penrose, claimed to be the greatest mathematical physicist alive writes; “To me the world of perfect forms is primary (as was Plato’s own belief) – its existence being almost a logical necessity – and both the other two worlds are its shadows.”[6] David Bohm agrees; “it is commonly believed that the content of thought is in some kind of reflective correspondence with ‘real things’, perhaps being a copy, or image, or imitation of things, perhaps a kind of ‘map’ of things, or perhaps (along the lines similar to those suggested by Plato) a grasp of the essential and innermost forms of things.”[7] In discussing implications of quantum physics Popper concludes that: “As with Plato the emphasis upon antecedent causes and geometrical cosmology is preserved.”[8] Platonic epistemology then stress that rational intuition is the supreme state of mind and this is coherent with Kantian and Bergsonian doctrine, which will be elaborated in the succeeding paragraphs. Only two issues will be mentioned here: First, a very brief note on the divided line presented in the Republic and then an equally brief note on the unique world argument from Timaeus. The divided line is the backbone in Plato’s epistemology and it illustrates the relationship between rational intuition and discursive thinking. The unique world argument is utterly intuitive and it is thus instrumental in revealing additional aspects of Plato’s view on intuition. The latter is included for a second purpose. The intent is that it will facilitate my interpretation of Kant’s account on intuition. The synopsis given is derived mainly from the works of Francis M. Cornford.[9]



The Divided Line

In Plato’s view, there are five stages of cognition, which are illustrated by a divided line and in the famous allegory of the cave. The realm of sensible appearances and shifting beliefs is contrasted with the realm of the intelligible or the eternal and unchanging Forms. The former corresponds to some degree with Kant’s notion of a posteriori and the latter to a priori. Indeed, it also resonates with Bergson, and his distinction between physical and metaphysical science.[10] Moreover, we might say that elements of this classical distinction, is still with us, but now turned upside down in the notions of conscious and unconscious. That is, intuition used to be equivalent with supreme rationality and intelligence while it is now often related to unconscious, biased, irrational and automatic processing. This ‘Copernican reversal’ in our history of epistemology is an issue we will return to in the chapter on intuition in psychology. The vertical line then, is divided into two main parts whose inequality symbolizes that the visible world has a lower degree of reality and truth than the intelligible.[11] The two parts also correspond to two faculties of mind: Knowledge of the real and Belief in appearances, both of which differ in clearness and certainty.[12]

                        Objects                                                           States of Mind




RATIONAL   INTUITION                 Noesis

KNOWING                                       Episteme

DISCURSIVE   THINKING               Dianoia



BELIEF                                               Pistis

IMAGINING                                     Eikasia




Specifically then, the lowest form of cognition is called eikasia. “The word defies translation, being one of those current terms to which Plato gives a peculiar sense, to be inferred from the context. It is etymologically connected with eikon, which means image or likeness, and with eikos, which means likely. Thus, it can mean likeness (representation), likening (comparison) or estimation of likelihood (conjecture).” Cornford suggests imagining as the least unsatisfactory rendering. “It seems to be the wholly unenlightened state of mind, which takes sensible appearances and current moral notions at their face value.” This state of mind is comparable to those in the cave who see only images of images, he argues.[13] Plato’s exact wording may provide additional information: “One of the two sections in the visible world will stand for images. By images I mean first shadows, and then reflections in water, or in close-grained, polished surfaces, and everything of that kind.”[14]



The higher section of physical appearances corresponds to common-sense belief or pistis. “It is a belief in the reality of the visible and tangible things commonly called substantial. In the moral sphere it would include ‘correct beliefs without knowledge’.” True beliefs are sufficient guides for action, but are insecure until based on knowledge of the reasons for them, Cornford points out.[15] Again, Plato’s own words are: “Let the second section stand for the actual things of which the first are likenesses, the living creatures about us and all the works of nature and of human hands. Will you also take the proportion in which the visible world has been divided as corresponding to degrees of reality and truth, so that the likeness shall stand to the original in the same ratio as the sphere of appearances and belief to the sphere of knowledge.”[16] Here it is made explicit to us that there is a similarity and correspondence in and between all levels of reality. The challenge for the philosopher is for her to intuit this.



Discursive Thinking

The focus of higher intellectual training then, is to detach the mind from individual appearances, and to familiarize it with the universal and the a priori, to use Kantian terminology. Higher education is to facilitate an escape from the prison of physical appearances by training the intellect, first in mathematics and then in moral philosophy. The use of visible diagrams and mathematical models as imperfect illustrations of the Forms is instrumental as a bridge carrying the mind across from the visible to the intelligible, Cornford argues. The mind must learn to distinguish between the two. Each branch of mathematics starts from unquestioned assumptions i.e. postulates, axioms, definitions and reasons from them, deductively. The premises may be true and the conclusions may follow but the whole structure hangs in the air until the assumptions themselves are shown to depend on an unconditioned principle.[17] Such a state of mind is called dianoia, which is the ordinary word for thought or thinking. For Plato dianoia is reasoning from unquestioned premises to conclusion, it is equivalent to discursive thinking and it falls short of perfect knowledge, Cornford argues.[18] It is similar to Kant’s verstand and it is a point we will return to later.

Because these historical sections on discursive thinking, knowledge and intuition are of special relevance to our reading of Kant and Bergson, as well as for later chapters, the entire argument is included. In considering how to divide the part, which stands for the intelligible world, Plato delineates three sections. In the first section of discursive thinking, “the mind uses as images those actual things which themselves had images in the visible world and it is compelled to pursue its inquiry by starting from assumptions and travels not up to a principle but down to a conclusion. In the second section of knowledge the mind moves in the other direction, from an assumption up towards a principle which is not hypothetical; and it makes no use of the images employed in the other section but only of Forms and conducts its inquiry solely by their means.”[19] When we later turn to Bergson, we will see that he is advocating a similar view. He states that intuition and the discursive activity of our intellect are not different organs but two sides of the same thinking activity. An activity powered by the spirit. The thinking activity goes in one direction when it applies a discursive, conceptual, quantitative, analytic and external perspective and in the opposite direction when it intuitively sympathizes with the metaphysical and psychological reality. Plato also gives an example illustrating how discursive thinking works:

“You know, of course, how students of subjects like geometry and arithmetic begin by postulating odd and even numbers, or the various figures and the three kinds of angle, and other such data in each subject. These data they take as known; and having adopted them as assumptions, they do not feel called upon to give any account of them to themselves or to anyone else, but treat them as self-evident. Then, starting from these assumptions, they go on until they arrive, by a series of consistent steps, at all the conclusions they set out to investigate. You also know how they make use of visible figures and discourse of them, though what they really have in mind is the originals of which these figures are images: they are not reasoning, for instance, about this particular square and diagonal which they have drawn, but about the square and the diagonal; and so in all cases. The diagrams they draw and the models they make are actual things, which may have their shadows or images in water; but now they serve in their turn as images, while the student is seeking to behold those realities which only thought can apprehend. This then, is the class of things that I spoke of as intelligible, but with two qualifications: first, that the mind, in studying them, is compelled to employ assumptions, and because it cannot rise above these, does not travel upwards to a first principle; and second, that it uses as images those actual things which have images of their own in the section below them and which, in comparison with those shadows and reflections, are reputed to be more palpable and valued accordingly.”[20]



Dianoia suggests discursive thinking, or reasoning from unquestioned premises to conclusion, whereas noesis is constantly compared to the immediate act of vision and suggests rather the direct intuition or apprehension of its object, Cornford argues.[21] The method or technique of discursive thinking is contrasted with the one of true knowledge and rational intuition, which is dialogue. Dialogue then, is a philosophic conversation carried on by question and answer, and seeking to render, or to receive from a respondent an account of some Form.[22] In this participatory state of mind visible illustrations are no longer available and the movement is not downward, deducing conclusions from premises, but upward examining the premises themselves and seeking the ultimate principle on which they all depend. It is suggested that if the mind could ever rise to grasp the supreme Form, The Good, it might then descend by a deduction confirming the whole structure of moral and mathematical knowledge. This state of mind is called rational intuition or intelligence and knowledge in the full, perfect sense, that is, episteme.[23] Plato maintains that: “Then by the second section of the intelligible world you may understand me to mean all, that unaided reasoning apprehends by the power of dialogue, when it treats its assumptions, not as first principles, but as hypotheses in the literal sense, things ‘laid down’ like a flight of steps up which it may mount all the way to something that is not hypothetical, the first principle of all; and having grasped this, may turn back and, holding on to the consequences which depend upon it, descend at last to a conclusion, never making use of any sensible object, but only of Forms, moving through Forms from one to another, and ending with Forms.”[24] This sentence is signifying a main position in European epistemology, namely that intuition is to be understood as a state of mind able to achieve an intelligent and rational comprehension of the intimate interplay of Reason and that which comes about of Necessity. In yet other words it perceives the intrinsic relationship between spirit and matter.

As dialogue is pivotal a fuller account could be appreciated.[25] However, here we must limit ourselves to Plato’s comments. The defect of the studies occupying discursive thinking is that the various branches are not seen synoptically as one connected whole. The object of dialogue is to secure a final confirmation and a synoptic view of all mathematical knowledge in connexion with the whole of reality, Cornford argues.[26] We can relate this to Kant’s synthetic method and to Bergson’s metaphysical method, another point that we will hold in reserve. Plato inherited this method from Socrates. Normally the respondent is putting forward his hypothetical attempts at analysis or definition of the concept in the form of necessary and sufficient conditions that are thought to capture all and only instances of the concept in question. Socrates then refutes the definition by pointing out various counterexamples. That is situations, where the proposed definition yields a result that conflicts with our intuition about the concept in question. In this way Socrates is facilitating improvement of the definition. Justice for example, is defined as “nothing more nor less than telling the truth and paying back anything we have received.” Socrates responds that: “Suppose, for example, a friend who had lent us a weapon were to go mad and then ask for it back, surely anyone would say we ought not to return it. It would not be ‘right’ to do so; nor to tell the truth without reserve to a madman.”[27] It would be unjust. After a proposed analysis or definition is overturned, dialogue continues until the definition is immune to intuitive counterexamples. On a side- note we should add that in this method is seen the seeds of many connotations attached to intuition for instance its global, unique, absolute, and integral character. Also, in the chapter on intuition and rationality it is argued that the later Plato refines this method in such a way that it differs slightly from the Socratic approach.

Plato then argues that: “At any rate, no one will maintain against us that there is any other method of inquiry which systematically attempts in every case to grasp the nature of each thing as it is in itself. .. . When the eye of the soul is sunk in a veritable slough of barbarous ignorance, this method gently draws it forth and guides it upwards. .. . It is not the what kind but the what that the soul seeks to know.”[28] Here we learn that Plato is more optimistic than Kant is, in terms of knowing the thing in itself. It is also clear that it is with the eye of the soul that we can intuit it. This organ of perfect knowledge must be turned around from the world of physical appearances together with the entire soul, until the soul is able to endure the contemplation in the brightest region of being and the intelligible world.[29] Episteme, or perfect knowledge as revealed by rational intuition is thus to be found by looking primarily not out but in to the psychological reality, a point emphasized by Bergson and Jung as well.


Rational Intuition

As a further refinement of his view on perfect intelligence and utmost reality Plato elaborates on the Good as the highest object of knowledge. However, this upper section of the intelligible world is not easily unveiled. On the contrary it represents the philosopher’s stone and Socrates refutes to define it. “The apprehension of it is rather to be thought of as a revelation which can only follow upon a long intellectual training.”[30] According to Cornford this supreme Good makes the world intelligible just like a work of human craftsmanship becomes intelligible when we see the purpose it is designed to serve. “As thus illuminating and accounting for the rational aspect of the universe the Good is analogous to the Sun, which, as the source of light is the cause of vision and of visibility and also of all mortal existence.”[31]

Plato starts his peculiar line of reason by pointing to the fact that hearing and sound do not stand in need of any third thing, without which the ear will not hear, nor sound be heard. The same is true for all the other senses, except the eyes. “You may have the power of vision in your eyes and try to use it, and colour may be there in the objects; but sight will see nothing and the colours will remain invisible in the absence of a third thing peculiarly constituted to serve this very purpose.”[32] By analogy Plato thus alludes to the rationale that in the visible world the Sun stand in the same relation to vision and visible things, as the Good itself bears in the intelligible world to rational intuition and intelligible objects. The next step in his reasoning is the crucial one of the mind’s orientation. “When you look at the colours of things irradiated only by the fainter luminaries of the night the eyes are dim. When the Sun is shining, the same eyes see distinctly.” This comparison is then applied to the soul. “When its gaze is fixed upon an object irradiated by truth and reality, the soul gains understanding and knowledge and is manifestly in possession of intelligence. But when it looks towards the twilight world of things that come into existence and pass away, its sight is dim and it has only opinions and beliefs which shift to and fro, and now it seems like a thing that has no intelligence.”[33]

Having established the importance of right orientation of the mind, Plato concludes that: “This, then, which gives to the objects of knowledge their truth and to him who knows them his power of knowing, is the Form or essential nature of Goodness. It is the cause of knowledge and truth; and so, while you may think of it as an object of knowledge, you will do well to regard it as something beyond truth and knowledge and, precious as these both are, of still higher worth.”[34] Moreover, the final and subtle point is this: “The Sun not only makes the things we see visible, but also brings them into existence and gives them growth and nourishment; yet he is not the same thing as existence. And so with the objects of knowledge: these derive from the Good not only their power of being known, but their very being and reality; and Goodness is not the same thing as being, but even beyond being, surpassing it in dignity and power.”[35] We may thus suggest that in Plato’s view rational intuition is functioning a little like the illuminated film lens in a cinema, accompanied as it is by the mind of the producer. In this account we also recognize the many theories about the enlightened mind and the speculations about a ‘third eye’, first popularised by Descartes who identified it with the pineal gland.

These then, are the essential arguments of the brief epistemology of Plato. However, the allegory of the cave adds some vital information. Unfortunately, there is no room for it here, but we may include a key point emphasized by Thomas Kuhn, in his insightful exposition of scientific revolutions; “Imagine what would happen if he went down again to take his former seat in the cave. Coming suddenly out of the sunlight, his eyes would be filled with darkness. He might be required once more to deliver his opinion on those shadows, in competition with those prisoners who had never been released, while his eyesight was still dim and unsteady. They would laugh at him and say that he had gone up only to come back with his sight ruined; it was worth no one’s while even to attempt the ascent. If they could lay hands on the man who was trying to set them free and lead them up, they would kill him.”[36]


The Unique World Argument

Every thing in the phenomenal world of appearances is in an incomplete way, part of the manifold of Forms, according to Plato. That is, in the Archetypes, to use Jung’s terminology. The Forms on the other hand are complete, their reciprocal relation being a well-defined and unambiguous one. Rational intuition then, may be understood as an increasing awareness of this synthetic or integral relationship, a point emphasized by Kant and Bergson, as well. The unique world argument then, serves as perhaps the best example given by Plato, on how the world of appearances participates in the intelligible world of Being and Forms. If we understand it, we may reveal aspects of the ‘true’ nature of intuition, as defined by philosophers. We will return to it in the chapter on intuition and rationality.

“What was the living creature in whose likeness he framed the world? We must not suppose that it was any creature that ranks only as a species, for no copy of that which is incomplete can ever be good. Let us rather say that the world is like, above all things, to that Living Creature of which all other living creatures, severally and in their families, are parts. For that embraces and contains within itself all the intelligible living creatures, just as this world contains ourselves and all other creatures that have been formed as things visible. For the god, wishing to make this world most nearly like that intelligible thing, which is best and in every way complete, fashioned it as a single visible living creature, containing within itself all living things whose nature is of the same order.”[37]

The argument is full of oddities. We are told that the kind, of which the world is the only instance, is living-thing-in-general. The world as a whole is one living thing, the World-Animal. Though, it is not any particular species or specific kind of living thing, it is rather a singular whole. This is a point of some importance to my interpretation of Kant, and his definition of intuition as a singular representation. Because the world is one single undivided whole and a unique copy of that living creature which embraces and contains all other living creatures, it is both individual and universal. It is a synthetic relationship between its individual traits and its universal traits. It is single, but not separated. It is unique, and embedded. It partakes of as well as in, much like a white wave-crest in a black wave. “The argument is remarkable in the sense that it is one of only a few passages in the Platonic corpus, which deal simultaneously with relations both between a Form and its phenomenal representations, and between Forms.”[38] Forms are portrayed canonically as paradigms and the relation of Form to particular is portrayed canonically as that of likeness, or more precisely, as the relation of original to image. [39] This is also the case in holography, which by Pribram is suggested as a model of how intuition works.[40]



Before we turn to Kant and Bergson, who argue that time and intuition have an intrinsic relationship, though without saying much about time, we should take note of Plato’s view. “Time came into being together with the Heaven, in order that, as they were brought into being together, so they may be dissolved together.” In virtue then, of this plan and intent of the god, for the birth of Time, the planets were made to define and preserve the numbers of time. Moreover, the planets are living creatures with an intelligent soul, and they are bound together with living bonds. The month comes to be when the Moon completes her own circle and overtakes the Sun; the year, when the Sun has gone round his own circle, it is argued. “The periods of the rest have not been observed by men, save for a few; and men have no names for them, nor do they measure one against another by numerical reckoning. They barely know that the wanderings of these others are time at all, bewildering as they are in number and of surprisingly intricate pattern.”[41] With Plato then, we have the somewhat puzzling conclusion, that supreme intelligence and rational intuition is able to look directly at the Sun and contemplate its nature, not as it appears when reflected in water or any alien medium, but as it is in itself, in its own domain. This is achieved by the eye of the soul looking primarily not out on the world of physical appearances but in to the universal domain of Forms.[42] Turning then to Kant who anchors the Forms of Plato in the individual as inherent and innate Forms that we synthesize with the empirical material provided by the senses, we find ourselves in an individualized version of Plato’s more universal approach.



[1] Emilsson, 2000, p. 1. See also Parkinson, 2000, p. 287-309, Gosling, 1973 and Tredennick, 1933.

[2] To Kant idealism is every system, which maintains that the sensible world does not exist in the form in which it presents itself to us. This position is typified in Kant’s mind, by e.g. Plato and Descartes, who are rationalists.

[3] Emilsson, 2000, p. 1.

[4] Ibid. See also Resnik & Orlandi, 2003, p. 305.

[5] Vlastos, 1975.

[6] Penrose, 1994, p. 414-417. He refers to the mental and physical world.

[7]   Bohm, 1981, p. 53. See also Bohm, 1993, 1994, Hannay, 1990, Jahn, 1987 and Hawking, 1988.

[8] Popper, 1989, p. 189, 206. See also Heisenberg, 1971, 1979, Churchland, 1984 and Capra, 1996.

[9] Cornford and Taylor are recognized as main authorities on Plato’s cosmology. See Taylor, 1928.

[10] Kolstad, 1998, p. 110. For Bergson, the scientific method primarily requires use of the intellect, while intuition is especially suitable when the metaphysical method is in use. The former is inclined to study the material, the latter the spiritual.

[11] Each part is then subdivided in the same proportion as the whole line. If imagining is A, belief B, discursive thinking C, and knowledge D, we have that A+B : C+D =   A:B = C:D.

[12] Cornford, 1955, p. 176. See also Shorey, 1935, 509D-511E, p. 104-117. The lower part of the line is by Plato first called the visible, but later the field of doxa. Both opinion and belief are inadequate, he argues. “Doxa and its cognates denote our apprehension of anything that seems to exist, like sensible appearances and phenomena.” It also includes that which seems to be true like opinions or beliefs, and what seems right e.g. legal and deliberative decisions, and the many conventional notions of current morality, which vary from place to place and from time to time.

[13] Ibid. p. 217.

[14] Ibid. p. 219.

[15] Ibid. p. 217-218.

[16] Ibid. My italics.

[17] This principle may be conjectured to be Unity itself, Cornford argues.

[18] Cornford, 1955, p. 218.

[19] Ibid. p. 219.

[20] Ibid. p. 220. My italics.

[21] Ibid. p. 218.

[22] Ibid. The higher method is in the text called Dialectic, a word, which since Hegel has acquired misleading associations. In the Republic, it simply means dialogue, Cornford argues.

[23] Ibid. p. 218-219.

[24] Ibid. p. 221.

[25] Bohm, 1996. See this book for elaboration of Dialogue.

[26] Cornford, 1955, p. 245.

[27] Ibid. p. 7.

[28] Ibid. p. 248. My italics.

[29] Ibid. p. 227. “There may well be an art, whose aim would be to effect this very thing, the conversion of the soul, in the readiest way; not to put power of sight into the soul’s eye which already has it, but to ensure that, instead of looking in the wrong direction, it is turned the way it ought to be.” See also Noddings & Shore, 1984.

[30] Ibid. p. 206. This being in flat contradiction to the Heuristic and bias tradition where intuition is considered a rapid, automatic, biased, effortless cognitive process. See Gilovich, Griffin, Kahneman, 2002, p. 51, 436-37.

[31] Ibid.

[32] Ibid. p. 212.

[33] Ibid. p. 213.

[34] Ibid. p. 214.

[35] Ibid.

[36] Ibid. p. 225-226. See Kuhn, 1975.

[37] Cornford, 1937, 30C-31B, p. 39-40. My italics.

[38] Mohr, 1985, p. 11-12. Mohr argues that in this passage, Plato’s deep intent is to show off the machinery of the Ideal theory. This because he in 33A, only two pages later, achieves his surface aim of showing that the world is unique, on grounds completely independent from, and much less contentious than those found at 30C-31B. There he simply argues that since the demiurge did not leave behind any materials unused in his crafting out of which another world might be formed, the world, which he did form, is necessarily unique. See also Mohr, 1986.

[39] The relevant paragraphs here are 31A and 30C-D. We may relate this passage to what we read on the Smaragdine Table, and indicate an Hermetic influence; “True, without error, certain and most true; that which is above is as that which is below, and that which is below is as that which is above, for performing the miracles of the One Thing; and as all things are from one, by the mediation of one, so all things arose from this one thing by adaptation ….” Randolph, 1871, p. 1. For a modern discussion, see Gilovich et al. 2002, p. 203.

[40] Pribram, 1971, 1991, 1998. See also Pribram, in Gunter, 1987, p. 171, and Talbot, 1991.

[41] Cornford, 1937, 38C-39E, p. 60. See also Winfree, 1987 and Sorabji, 1983, for a modern exposition of Time.

[42] Cornford, 1955, 514A-521B, p. 225. Such an intimate correspondence and interplay between macrocosm and microcosm, was for the Greeks firmly embedded in the art of astrology, and it continued its influence all the way up to Newton and Kepler, who published books on the issue in 1602.